Novel catalysts of phosphotungstic heteropolyacids (PW12) supported on neutral alumina were prepared by assistance of ultrasound and plasma treatment. The prepared catalysts were characterized by FT-IR pyridine adso...Novel catalysts of phosphotungstic heteropolyacids (PW12) supported on neutral alumina were prepared by assistance of ultrasound and plasma treatment. The prepared catalysts were characterized by FT-IR pyridine adsorption (Py-IR), temperature programmed desorption of Pyridine (Py-TPD), BET and X-ray diffraction (XRD), and their catalytic performances were evaluated by the cationic polymerization of tetrahydrofuran. The results indicate that plasma treatment remarkably increases the surface acidity of the prepared catalyst while ultrasonic treatment induces PW12 to uniformly disperse on the support surface and expose more active sites for the acid catalytic reaction. A higher catalytic activity (69.7%) is obtained on the novel catalyst, which significantly outstripped that on the conventional sample (57.5%).展开更多
TiO2 sol was prepared by sol-gel technique with tetrabutyl titanate as precursor. Supported TiO2 catalysts on activated carbon were prepared by soak and sintering method. The aggregation of nano-TiO2 particles can be ...TiO2 sol was prepared by sol-gel technique with tetrabutyl titanate as precursor. Supported TiO2 catalysts on activated carbon were prepared by soak and sintering method. The aggregation of nano-TiO2 particles can be effectively suppressed by added polyethylene glycol (PEG) as a surface modifier. The average particle diameter of TiO2, specific surface area and absorbability of catalyst can be modified. Based on characteristics of the TiO2 photocatalyst with XRD, specific surface area, adsorption valves of methylene blue and the amount of TiO2 supported on the activated carbon, the photocatalytic degradation of L-acid was studied. The effect of the factors, such as pH of the solution, the initial concentration of L-acid on the photocatalytic degradation of L-acid, were studied also. It was found that when the pH of the solution is 1.95, the amount of photocatalyst is 0.5 g, the concentration of the L-acid solution is 1.34×10^3 mol/L and the illumination time is 7 h, the photocatalytic degradation efficiency of L-acid can reach 89,88%, The catalyst was reused 6 times and its degradation efficiency hardly changed.展开更多
Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste. We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%)...Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste. We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%) as nitrating agent, and found that supported sulfuric acid catalyst exhibited a very high catalytic activity. Under the conditions of reaction temperature 160-170℃, space velocity (SV) 1200 h-1, the yield and the space-time yield (STY) of nitrobenzene (NB) based on HNO3 were more than 98% and 0.75 kg穔gcat-1穐-1 over 10% H2SO4/SiO2 (by weight) catalyst respectively.展开更多
The optical alpha-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine ...The optical alpha-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine (or quinine) alkaloids as chiral phase transfer catalysts and dichloromethane as solvent, followed by hydrolysis of the above intermediates introduced to the final products-optical alpha-amino acids. This is a new method for the asymmetric synthesis of alpha-amino acids. The influences of catalyst, temperature, substrates, and organic solvents on the chemical yield and optical purities of products were studied.展开更多
A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn (Ⅳ)/g ca...A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn (Ⅳ)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.展开更多
Potassium and cesium salts of tungstophosphoric acid were prepared by precipitation method. For sake of comparison HPW, potassium and cesium tungstophosphates were supported on silica (20 wt%) by wet impregnation meth...Potassium and cesium salts of tungstophosphoric acid were prepared by precipitation method. For sake of comparison HPW, potassium and cesium tungstophosphates were supported on silica (20 wt%) by wet impregnation method. The catalysts were characterized by XRD, nitrogen adsorption-desorption measurements at 77 K, and the catalytic activity has been studied by using the catalytic conversion of tert-butanol at temperatures between 323 and 423 K. The results revealed that all of the catalysts were active and selective towards dehydration of tert-butanol yielding isobutene with low amount of isooctene as result of oligomerization process. Substitution of one proton of HPW by cesium or potassium cation exerted no measurable effect on the catalytic activity. The conversion over unsupported catalysts increased by increasing the cation content per Keggin unit of x ≥ 2. Supporting the previous salts on SiO2 resulted in a significant decrease in the catalytic activity upon increasing cation content. Activation energy was calculated for different solids.展开更多
A silica-supported cross-linked poly(maleic acid -co- styrene)-platinum complex (PMS-Pt) has been prepared and found to be active in the hydrogenation of p-cresol under mild conditions (303-323K, 1.01 x 10(5)Pa). In t...A silica-supported cross-linked poly(maleic acid -co- styrene)-platinum complex (PMS-Pt) has been prepared and found to be active in the hydrogenation of p-cresol under mild conditions (303-323K, 1.01 x 10(5)Pa). In this hydrogenation system water serves as a solvent and p-cresol can be converted to 4-methylcyclohexanol quantitatively via 4-methylcyclohexanone as intermediate.展开更多
The polystyrene supported glutamic acid Schiff base complex of Mn (Ⅱ) (PS-Sal-Glue-Mn) was prepared with chloromethylated styrene polymer beads, 2,4-dihydroxybenzaldehyde, L-glutamic acid and manganese (Ⅱ) acetate t...The polystyrene supported glutamic acid Schiff base complex of Mn (Ⅱ) (PS-Sal-Glue-Mn) was prepared with chloromethylated styrene polymer beads, 2,4-dihydroxybenzaldehyde, L-glutamic acid and manganese (Ⅱ) acetate tetrahyrate. The polymeric ligand and the complex were characterized by FT-IR, small area X-ray photoelectron spectroscopy (XPS) and ICP-AES. In the presence of the manganese complex, cyclohexene (1) was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol (2), 2-cyclohexen-1-one (3) and 2-cyclohexen-1- hydroperoxide (4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-1-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.展开更多
The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(...The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the transport of Tb(III) have also been investigated, respectively. As a result, the optimum transport conditions of Tb(III) were obtained, i.e., the concentration of HCl solution was 4.0 mol/L, the concentration of D2EHPA was 0.16 mol/L, the volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase and pH value was 4.5 in the feed phase. Ionic strength had no obvious effect on the transport of Tb(III). Under the optimum conditions, the transport percentage of Tb(III) was up to 96.1% in a transport time of 35 min when the initial concentration of Tb(IIl) was 1.0× 10 -4 mol/L. The diffusion coefficient of Tb(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.82×10 -8 m2/s and 5.61 um, respectively. The calculated results were in good agreement with the literature data.展开更多
Supported ionic liquid(IL) sorbents for CO_2 capture were prepared by impregnating tetramethylammonium glycinate([N1111][Gly]) into four types of porous materials in this study. The CO_2 adsorption behavior was invest...Supported ionic liquid(IL) sorbents for CO_2 capture were prepared by impregnating tetramethylammonium glycinate([N1111][Gly]) into four types of porous materials in this study. The CO_2 adsorption behavior was investigated in a thermogravimetric analyzer(TGA). Among them, poly(methyl methacrylate)(PMMA)-[N1111][Gly]exhibits the best CO_2 adsorption properties in terms of adsorption capacity and rate. The CO_2 adsorption capacity reaches up to 2.14 mmol·g-1 sorbent at 35 °C. The fast CO_2 adsorption rate of PMMA-[N1111][Gly] allows 60 min of adsorption equilibrium time at 35 °C and much shorter time of 4 min is achieved at 75 °C. Further, Avrami's fractional-order kinetic model was used and fitted well with the experiment data, which shows good consistency between experimental results and theoretical model. In addition, PMMA-[N1111][Gly] remained excellent durability in the continuous adsorption–desorption cycling test. Therefore, this stable PMMA-[N1111][Gly] sorbent has great potential to be used for fast CO_2 adsorption from flue-gas.展开更多
Permeabilities and selectivities of gases such as carbon dioxide(CO2),sulfur dioxide(SO2),nitrogen(N2)and methane(CH4)in six imidazolium-based ionic liquids([emim][BF4],[bmim][BF4],[bmim][PF6],[hmim][BF4],[bmim][Tf2N]...Permeabilities and selectivities of gases such as carbon dioxide(CO2),sulfur dioxide(SO2),nitrogen(N2)and methane(CH4)in six imidazolium-based ionic liquids([emim][BF4],[bmim][BF4],[bmim][PF6],[hmim][BF4],[bmim][Tf2N]and[emim][CF3SO3])supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45oC and pressure of N2 from 100 to 400kPa.It is found that SO2 has the highest permeability in the tested supported ionic liquid membranes,being an order of magnitude higher than that of CO2,and about 2 to 3 orders of magnitude larger than those of N2 and CH4.The observed selectivity of SO2 over the two ordinary gas components is also striking.It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes,as well as the nature of ionic liquids play important roles in the gas permeation.A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases.By considering the factors that influence the permeabilities and selectivities of CO2 and SO2,it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.展开更多
In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were charac...In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.展开更多
Methacrylic acid first was neutralized with an aqueous solution of NaOH to pH = 6.0 similar to 7.0, vinylene carbonate (VCA) was added to the solution, then monomers were copolymerized in paraffin oil by means of reve...Methacrylic acid first was neutralized with an aqueous solution of NaOH to pH = 6.0 similar to 7.0, vinylene carbonate (VCA) was added to the solution, then monomers were copolymerized in paraffin oil by means of reverse-phase suspension polymerization and hydrophilic copolymeric supports were prepared. The properties of the supports were determined using trypsin and results show that the amount of enzymes coupled to the supports and the specific activity of immobilized trypsin are related to the content of VCA structure units, reaction time and concentration of enzyme solution, etc.展开更多
Efficient polymer supported synthesis of multi-substituted pyrimidine-4-one derivatives was described. Target products were produced from fluorenylmethoxycarbonyl(Fmoc) protected β-amino acid loaded on hydro- xymet...Efficient polymer supported synthesis of multi-substituted pyrimidine-4-one derivatives was described. Target products were produced from fluorenylmethoxycarbonyl(Fmoc) protected β-amino acid loaded on hydro- xymethyl resin through deprotection, N-alkylation, guanidine formation, and cleavage of 2,2,4,6,7-pentamethyl dihy-drobenzofuran-sulfonyl(Pbf) by trifluoracetic acid(TFA) followed with cyclization. The procedure has the advantages of easy operation, mild reaction conditions, and forming multiple substituents.展开更多
A series of heterogeneous catalysts with Cp2TiCl2 supported on palygorskite were prepared and evaluated by ethylene slurry polymerizations. The so-called direct supported catalyst, for which the pretreatment of palygo...A series of heterogeneous catalysts with Cp2TiCl2 supported on palygorskite were prepared and evaluated by ethylene slurry polymerizations. The so-called direct supported catalyst, for which the pretreatment of palygorskite with MAO or Al(i-Bu)3 was not necessary, gave the highest activity among these supported catalysts and could be more robust than homogeneous Cp2TiCl2. With the direct supported catalyst, no significant activity loss was observed under low Al/Ti molar ratios (Al/Ti=300) and the decay of polymerization rate was slower when compared to the other supported catalysts. It was found that the surface Lewis acidity of palygorskite after thermal treatment played an important role in activation of metallocene compound and resulted in high catalyst activity.展开更多
The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and...The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in kerosene as the membrane solution, was studied. As a result, the optimum transport conditions of La(Ⅲ) were obtained as that concentration of HCl solution was 4.0 mol/L, concentration of PC-88A 0.16 mol/L, and volume ratio of membrane to stripping solution 30:30 in the dispersion phase, and pH value 4.0 in the feed phase. Ionic strength had no obvious effect on the transport of La(Ⅲ). Under the optimum conditions, when initial concentration of La(Ⅲ) was 0.8×10-4 mol/L, the transport rate was up to 96.3% during the transport time of 125 min. The kinetic equation was developed based on the law of mass diffusion and theory of interface chemistry. The diffusion coefficient of La(Ⅲ) in the membrane and the thickness of diffusion layer between feed and membrane phases were obtained as 3.20×10-7 m2/s and 3.22×10-5 m, respectively. The calculated results were in good agreement with experimental results.展开更多
BACKGROUND Sepsis exacerbates intestinal microecological disorders leading to poor prognosis.Proper modalities of nutritional support can improve nutrition,immunity,and intestinal microecology.AIM To identify the opti...BACKGROUND Sepsis exacerbates intestinal microecological disorders leading to poor prognosis.Proper modalities of nutritional support can improve nutrition,immunity,and intestinal microecology.AIM To identify the optimal modality of early nutritional support for patients with sepsis from the perspective of intestinal microecology.METHODS Thirty patients with sepsis admitted to the intensive care unit of the General Hospital of Ningxia Medical University,China,between 2019 and 2021 with indications for nutritional support,were randomly assigned to one of three different modalities of nutritional support for a total of 5 d:Total enteral nutrition(TEN group),total parenteral nutrition(TPN group),and supplemental parenteral nutrition(SPN group).Blood and stool specimens were collected before and after nutritional support,and changes in gut microbiota,short-chain fatty acids(SCFAs),and immune and nutritional indicators were detected and compared among the three groups.RESULTS In comparison with before nutritional support,the three groups after nutritional support presented:(1)Differences in the gut bacteria(Enterococcus increased in the TEN group,Campylobacter decreased in the TPN group,and Dialister decreased in the SPN group;all P<0.05);(2)different trends in SCFAs(the TEN group showed improvement except for Caproic acid,the TPN group showed improvement only for acetic and propionic acid,and the SPN group showed a decreasing trend);(3)significant improvement of the nutritional and immunological indicators in the TEN and SPN groups,while only immunoglobulin G improved in the TPN group(all P<0.05);and(4)a significant correlation was found between the gut bacteria,SCFAs,and nutritional and immunological indicators(all P<0.05).CONCLUSION TEN is recommended as the preferred mode of early nutritional support in sepsis based on clinical nutritional and immunological indicators,as well as changes in intestinal microecology.展开更多
基金the National Natural Science Foundation of China(No.205903603)the Ministry of Sciences and Technology of China(No.2005CB221406)the New Century Excellent Talent Project of Ministry of Education of China(No.CET-05-0783)
文摘Novel catalysts of phosphotungstic heteropolyacids (PW12) supported on neutral alumina were prepared by assistance of ultrasound and plasma treatment. The prepared catalysts were characterized by FT-IR pyridine adsorption (Py-IR), temperature programmed desorption of Pyridine (Py-TPD), BET and X-ray diffraction (XRD), and their catalytic performances were evaluated by the cationic polymerization of tetrahydrofuran. The results indicate that plasma treatment remarkably increases the surface acidity of the prepared catalyst while ultrasonic treatment induces PW12 to uniformly disperse on the support surface and expose more active sites for the acid catalytic reaction. A higher catalytic activity (69.7%) is obtained on the novel catalyst, which significantly outstripped that on the conventional sample (57.5%).
基金The State Education Ministry "211" Project, the Natural Science Foundation of the Education Commission of Jiangsu Province(2005103TSJB156) and the Funding of the Environment Friendship Laboratory of Nanjing Normal University
文摘TiO2 sol was prepared by sol-gel technique with tetrabutyl titanate as precursor. Supported TiO2 catalysts on activated carbon were prepared by soak and sintering method. The aggregation of nano-TiO2 particles can be effectively suppressed by added polyethylene glycol (PEG) as a surface modifier. The average particle diameter of TiO2, specific surface area and absorbability of catalyst can be modified. Based on characteristics of the TiO2 photocatalyst with XRD, specific surface area, adsorption valves of methylene blue and the amount of TiO2 supported on the activated carbon, the photocatalytic degradation of L-acid was studied. The effect of the factors, such as pH of the solution, the initial concentration of L-acid on the photocatalytic degradation of L-acid, were studied also. It was found that when the pH of the solution is 1.95, the amount of photocatalyst is 0.5 g, the concentration of the L-acid solution is 1.34×10^3 mol/L and the illumination time is 7 h, the photocatalytic degradation efficiency of L-acid can reach 89,88%, The catalyst was reused 6 times and its degradation efficiency hardly changed.
文摘Vapor-phase nitration of benzene over solid acid catalyst is expected to be a clean process with no sulfuric acid waste. We investigated this process over solid acidic catalysts utilizing diluted nitric acid (60-70%) as nitrating agent, and found that supported sulfuric acid catalyst exhibited a very high catalytic activity. Under the conditions of reaction temperature 160-170℃, space velocity (SV) 1200 h-1, the yield and the space-time yield (STY) of nitrobenzene (NB) based on HNO3 were more than 98% and 0.75 kg穔gcat-1穐-1 over 10% H2SO4/SiO2 (by weight) catalyst respectively.
基金Project supported by State Education Committee Initial Research Crams for Return Scholar and supported by NSFC No 29774012.
文摘The optical alpha-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine (or quinine) alkaloids as chiral phase transfer catalysts and dichloromethane as solvent, followed by hydrolysis of the above intermediates introduced to the final products-optical alpha-amino acids. This is a new method for the asymmetric synthesis of alpha-amino acids. The influences of catalyst, temperature, substrates, and organic solvents on the chemical yield and optical purities of products were studied.
文摘A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn (Ⅳ)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.
文摘Potassium and cesium salts of tungstophosphoric acid were prepared by precipitation method. For sake of comparison HPW, potassium and cesium tungstophosphates were supported on silica (20 wt%) by wet impregnation method. The catalysts were characterized by XRD, nitrogen adsorption-desorption measurements at 77 K, and the catalytic activity has been studied by using the catalytic conversion of tert-butanol at temperatures between 323 and 423 K. The results revealed that all of the catalysts were active and selective towards dehydration of tert-butanol yielding isobutene with low amount of isooctene as result of oligomerization process. Substitution of one proton of HPW by cesium or potassium cation exerted no measurable effect on the catalytic activity. The conversion over unsupported catalysts increased by increasing the cation content per Keggin unit of x ≥ 2. Supporting the previous salts on SiO2 resulted in a significant decrease in the catalytic activity upon increasing cation content. Activation energy was calculated for different solids.
文摘A silica-supported cross-linked poly(maleic acid -co- styrene)-platinum complex (PMS-Pt) has been prepared and found to be active in the hydrogenation of p-cresol under mild conditions (303-323K, 1.01 x 10(5)Pa). In this hydrogenation system water serves as a solvent and p-cresol can be converted to 4-methylcyclohexanol quantitatively via 4-methylcyclohexanone as intermediate.
文摘The polystyrene supported glutamic acid Schiff base complex of Mn (Ⅱ) (PS-Sal-Glue-Mn) was prepared with chloromethylated styrene polymer beads, 2,4-dihydroxybenzaldehyde, L-glutamic acid and manganese (Ⅱ) acetate tetrahyrate. The polymeric ligand and the complex were characterized by FT-IR, small area X-ray photoelectron spectroscopy (XPS) and ICP-AES. In the presence of the manganese complex, cyclohexene (1) was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol (2), 2-cyclohexen-1-one (3) and 2-cyclohexen-1- hydroperoxide (4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-1-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.
基金Supported by the National Natural Science Foundation of China(No90401009)the Natural Science Foundation of Shaanxi Province, China(NoSJ08B16)+1 种基金the Science Research Program of Education Department of Shaanxi Province, China (No06JK215)the Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology, China (No602-210805)
文摘The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the transport of Tb(III) have also been investigated, respectively. As a result, the optimum transport conditions of Tb(III) were obtained, i.e., the concentration of HCl solution was 4.0 mol/L, the concentration of D2EHPA was 0.16 mol/L, the volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase and pH value was 4.5 in the feed phase. Ionic strength had no obvious effect on the transport of Tb(III). Under the optimum conditions, the transport percentage of Tb(III) was up to 96.1% in a transport time of 35 min when the initial concentration of Tb(IIl) was 1.0× 10 -4 mol/L. The diffusion coefficient of Tb(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.82×10 -8 m2/s and 5.61 um, respectively. The calculated results were in good agreement with the literature data.
基金Supported by the National Basic Research Program of China(2013CB733503)the National Natural Science Foundation of China(21136001,21136004,21476106,21428601,21776123)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)and the Jiangsu Natural Science Foundation(BK20130062)
文摘Supported ionic liquid(IL) sorbents for CO_2 capture were prepared by impregnating tetramethylammonium glycinate([N1111][Gly]) into four types of porous materials in this study. The CO_2 adsorption behavior was investigated in a thermogravimetric analyzer(TGA). Among them, poly(methyl methacrylate)(PMMA)-[N1111][Gly]exhibits the best CO_2 adsorption properties in terms of adsorption capacity and rate. The CO_2 adsorption capacity reaches up to 2.14 mmol·g-1 sorbent at 35 °C. The fast CO_2 adsorption rate of PMMA-[N1111][Gly] allows 60 min of adsorption equilibrium time at 35 °C and much shorter time of 4 min is achieved at 75 °C. Further, Avrami's fractional-order kinetic model was used and fitted well with the experiment data, which shows good consistency between experimental results and theoretical model. In addition, PMMA-[N1111][Gly] remained excellent durability in the continuous adsorption–desorption cycling test. Therefore, this stable PMMA-[N1111][Gly] sorbent has great potential to be used for fast CO_2 adsorption from flue-gas.
基金Supported by the National Natural Science Foundation of China (20776065), the Natural Science Foundation of Jiangsu Province (BK2008023), and the National Found for Fostering Talents of Basic Science 00630425).
文摘Permeabilities and selectivities of gases such as carbon dioxide(CO2),sulfur dioxide(SO2),nitrogen(N2)and methane(CH4)in six imidazolium-based ionic liquids([emim][BF4],[bmim][BF4],[bmim][PF6],[hmim][BF4],[bmim][Tf2N]and[emim][CF3SO3])supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45oC and pressure of N2 from 100 to 400kPa.It is found that SO2 has the highest permeability in the tested supported ionic liquid membranes,being an order of magnitude higher than that of CO2,and about 2 to 3 orders of magnitude larger than those of N2 and CH4.The observed selectivity of SO2 over the two ordinary gas components is also striking.It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes,as well as the nature of ionic liquids play important roles in the gas permeation.A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases.By considering the factors that influence the permeabilities and selectivities of CO2 and SO2,it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.
文摘In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.
文摘Methacrylic acid first was neutralized with an aqueous solution of NaOH to pH = 6.0 similar to 7.0, vinylene carbonate (VCA) was added to the solution, then monomers were copolymerized in paraffin oil by means of reverse-phase suspension polymerization and hydrophilic copolymeric supports were prepared. The properties of the supports were determined using trypsin and results show that the amount of enzymes coupled to the supports and the specific activity of immobilized trypsin are related to the content of VCA structure units, reaction time and concentration of enzyme solution, etc.
基金Supported by the Scientific Forefront and Interdisciplinary Innovation Project of Jilin UniversityChina(No.421031531412)+1 种基金the Jilin Provincial Research Foundation for Basic Research China(No.3D109K856604)
文摘Efficient polymer supported synthesis of multi-substituted pyrimidine-4-one derivatives was described. Target products were produced from fluorenylmethoxycarbonyl(Fmoc) protected β-amino acid loaded on hydro- xymethyl resin through deprotection, N-alkylation, guanidine formation, and cleavage of 2,2,4,6,7-pentamethyl dihy-drobenzofuran-sulfonyl(Pbf) by trifluoracetic acid(TFA) followed with cyclization. The procedure has the advantages of easy operation, mild reaction conditions, and forming multiple substituents.
基金supported by the National Natural Science Foundation of China(No.20376069).
文摘A series of heterogeneous catalysts with Cp2TiCl2 supported on palygorskite were prepared and evaluated by ethylene slurry polymerizations. The so-called direct supported catalyst, for which the pretreatment of palygorskite with MAO or Al(i-Bu)3 was not necessary, gave the highest activity among these supported catalysts and could be more robust than homogeneous Cp2TiCl2. With the direct supported catalyst, no significant activity loss was observed under low Al/Ti molar ratios (Al/Ti=300) and the decay of polymerization rate was slower when compared to the other supported catalysts. It was found that the surface Lewis acidity of palygorskite after thermal treatment played an important role in activation of metallocene compound and resulted in high catalyst activity.
基金Supported by the National Natural Science Foundation of China (No.90401009)Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (No.602-210805)
文摘The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in kerosene as the membrane solution, was studied. As a result, the optimum transport conditions of La(Ⅲ) were obtained as that concentration of HCl solution was 4.0 mol/L, concentration of PC-88A 0.16 mol/L, and volume ratio of membrane to stripping solution 30:30 in the dispersion phase, and pH value 4.0 in the feed phase. Ionic strength had no obvious effect on the transport of La(Ⅲ). Under the optimum conditions, when initial concentration of La(Ⅲ) was 0.8×10-4 mol/L, the transport rate was up to 96.3% during the transport time of 125 min. The kinetic equation was developed based on the law of mass diffusion and theory of interface chemistry. The diffusion coefficient of La(Ⅲ) in the membrane and the thickness of diffusion layer between feed and membrane phases were obtained as 3.20×10-7 m2/s and 3.22×10-5 m, respectively. The calculated results were in good agreement with experimental results.
基金Supported by Ningxia Natural Science Foundation Project,No.2022AAC03488the National Key Research and Development Program of China,No.2016YFD0400605.
文摘BACKGROUND Sepsis exacerbates intestinal microecological disorders leading to poor prognosis.Proper modalities of nutritional support can improve nutrition,immunity,and intestinal microecology.AIM To identify the optimal modality of early nutritional support for patients with sepsis from the perspective of intestinal microecology.METHODS Thirty patients with sepsis admitted to the intensive care unit of the General Hospital of Ningxia Medical University,China,between 2019 and 2021 with indications for nutritional support,were randomly assigned to one of three different modalities of nutritional support for a total of 5 d:Total enteral nutrition(TEN group),total parenteral nutrition(TPN group),and supplemental parenteral nutrition(SPN group).Blood and stool specimens were collected before and after nutritional support,and changes in gut microbiota,short-chain fatty acids(SCFAs),and immune and nutritional indicators were detected and compared among the three groups.RESULTS In comparison with before nutritional support,the three groups after nutritional support presented:(1)Differences in the gut bacteria(Enterococcus increased in the TEN group,Campylobacter decreased in the TPN group,and Dialister decreased in the SPN group;all P<0.05);(2)different trends in SCFAs(the TEN group showed improvement except for Caproic acid,the TPN group showed improvement only for acetic and propionic acid,and the SPN group showed a decreasing trend);(3)significant improvement of the nutritional and immunological indicators in the TEN and SPN groups,while only immunoglobulin G improved in the TPN group(all P<0.05);and(4)a significant correlation was found between the gut bacteria,SCFAs,and nutritional and immunological indicators(all P<0.05).CONCLUSION TEN is recommended as the preferred mode of early nutritional support in sepsis based on clinical nutritional and immunological indicators,as well as changes in intestinal microecology.